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17 Cards in this Set
- Front
- Back
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alkyne carbon atoms are ___ hybridized
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sp
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The triple bond of an alkyne consists of one ____ and two _____
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one sp-sp sigma bond and two -p pi bonds
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What are the two best methods of alkyne synthesis?
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alkylation of an acetylide anion with a primary alkyl halide ad the twofold elimination of HX from a vicinal dihalide
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The chemistry of alkynes is dominated by _____
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electrophilic addition reactions, similar to those of alkenes
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Alkynes react with HBr and HCl to yield ______
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vinylic halides
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Alkynes react with Br2 and Cl2 to yield ______
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1,2-dihalides (vicinal dihalides)
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Alkynes can be hydrated by reaction with _____ in the presence of ____
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aqueous sulfuric acid in the presence of mercury (II) catalyst
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Alkynes can be hydrated by reaction with aqueous sulfuric acid in the presence of ercury (II) catalys The reaction leads to an intermediate ____ that immediate ____
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enol, that immediately isomerizes to yield a ketone tautomer.
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By Marki's rule, a methyl ketone is produced from a ____
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terminal alkyne
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By anti-Marki, hydroboration/oxidation of a terminal alkyne yields ___
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an aldehyde
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Alkynes can be reduced to yield
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alkenes and alkanes
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explain complete reduction
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Complete reduction f the triple bond over a palladium hydrgenation catalyst yileds a alkane
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explain partial reduction of alkynes
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Partial reduction by catalytic hydrogenation over a lindlar catalyst yields a CIS alkene. Ruduction o the alkyne with lithium in ammonia yields a trans alkene.
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terminal alkynes are ___ acidic
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weakly
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Because terminal alkynes are weakly acidic, the alkyne hydrogen can be removed by
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a strong base such as Na+-H2 to yield an acetylide anion
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an acetylide anion acts as a___
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nuclephile and can dispace a halide ion from a primary alkyl halide in an alkylation reaction
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acetylide anions are more stable than either alkyl anions or vinylic anions because
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their negative charge is in a hybrid orbital with 50%s character, allowing the charge to be loser to the nucleus.
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